This invention relates to gas meters and more particularly to a gas meter of the bellows type.
These meters are well known and one embodiment is described in British Pat. No. 1 508 307. It consists essentially of two measurement spaces, each space being separated into two measurement chambers by a deformable bellows. Each measurement chamber has an orifice for the admission and exhaustion of the gas to be measured.
To synchronize the admission and exhaustion of the gas in the chambers with the position of the bellows, each bellows is associated with a transmission system which controls a distributor which cyclically places the orifices associated with the chambers in communication with the gas inlet into the meter or with the gas outlet.
The distributor can be of the linear displacement type, as in the case of the meter described in the British patent mentioned above, or of the rotary displacement type. In the latter case, the orifices associated with the chambers are arranged on a circular ring and the distributor rotates about the axis of this ring.
The distributor slides on a slide face in which are provided orifices, and the sealing between the distributor and the slide face is provided only by the weight of the distributor and by the difference in gas pressure within the distributor and outside of it owing to pressure drops. To obtain good sealing, a requirement for obtaining a meter having good accuracy, it is necessary for the wear on the face of the distributor in contact with the slide face to be regular. However, in prior-art systems, the distributor drive means introduce an additional tilting torque on the distributor, i.e., in addition to rotation of the distributor about its axis perpendicular to the slide face, the drive means apply a torque to the distributor tending to make it turn around an axis perpendicular to its normal axis of rotation. This results in irregular wear on the bearing surface of the distributor and produces leaks, thus preventing correct operation of the gas meter.